Sanitary napkins are well known in the art. Sanitary napkins intercept menses upon discharge, and thereby protect the clothing and bedding of the wearer from soiling due to the menses. However, oftentimes the sanitary napkin can shift in use and the menses will not hit the target area. Additionally, improved menses interception can occur if the sanitary napkin is in close contact with the body of the wearer.
Several attempts have been made in the art to improve body contact with the wearer, and hence absorb menses upon discharge and thereby minimize soiling by providing a sanitary napkin having a convex upward configuration. Examples of such attempts are illustrated in U.S. Pat. No. 2,747,575 issued May 29, 1956 to Mercer; U.S. Pat. No. 3,343,543 issued Sep. 26, 1967 to Glassman; U.S. Pat. No. 5,171,302 issued Dec. 15, 1992 to Buell; and U.S. Pat. No. 5,197,959 issued Mar. 30, 1993 to Buell. The two patents issued to Buell are incorporated herein by reference. However, Glassman suffers from drawbacks which are significant in sanitary napkins successfully commercialized today, and further improvements are possible over Buell.
For example, Mercer requires the sanitary napkin to have stitching through its thickness to achieve a longitudinal medial hump. Stitching a sanitary napkin according to today's construction is simply infeasible due to the materials now utilized. Also this process is prohibitively slow and costly.
Glassman requires the sanitary napkin to have longitudinal troughs on the top surface of the sanitary napkin formed by mechanical compression or cutting slits. This sanitary napkin further has a compression formed continuous groove which may or may not include the moisture resistant covering on the back of the sanitary napkin. The groove allows the sanitary napkin to fold into an inverted U-shape. The longitudinal groove, however, does not promote concave cupping of the front of the sanitary napkin around the mons pubis of the wearer and does not fit into the gluteal groove. More importantly, the continuous longitudinal groove prevents the sanitary napkin from having resiliency. Resiliency is the ability of the sanitary napkin to return to an uncompressed configuration when external deformation forces, such as the lateral pressure of the wearer's thighs, are removed. It is important that the sanitary napkin have resiliency, in order that the target area remain as large as possible, and menses does not strike the clothing of the wearer. Furthermore, the compressed groove will have a lower rate of absorbency or a lesser capacity.
Buell teaches a sanitary napkin having a deformation element with flexure hinges. The deformation element is a moldable substance such as foam and may be reformable or resilient. The deformation element and hence the sanitary napkin deforms into a W-shaped cross-section in response to lateral pressure from the wearer's thighs. The deformation element, similar to the Mercer stitching, requires an additional component to be added to the sanitary napkin, thus increasing its cost.
Furthermore, none of these attempts are suitable with particular sanitary napkins which today are commercially successful. Today's sanitary napkins frequently incorporate superabsorbents, have a caliper less than 5 millimeters, and frequently a caliper less than 3 millimeters. Such a sanitary napkin cannot readily be stitched, as taught by Mercer, due to the materials are too thin and lack strength sufficient to support the stitching. Stitching in the Z-direction is infeasible, as well as prohibitively slow and costly. Similarly, sanitary napkins will neither form a cup shape around the mons pubis of the wearer, nor be resilient if grooved on the underside because they are too flexible along the entire longitudinal length. Finally, a deformation element cannot be added to such a sanitary napkin as the caliper would significantly increase. Increased caliper increases the wearer's awareness of the sanitary napkin and decreases her comfort.
Accordingly, it is an object of this invention to provide a sanitary napkin which provides a convex upwardly facing cross-section. It is further an object of this invention to provide a sanitary napkin which is concave towards the mons pubis of the wearer. It is finally an object of this invention to provide a sanitary napkin which has resiliency without adding a separate element.